1. Field of Invention
This invention is directed to a method and an apparatus to facilitate minimally invasive measurement, sampling and/or sensing of analytes, for example, glucose, in a fluid, matrix or animal body.
2. Description of the Related Art
Glucose sensing is an important diagnostic tool in therapy and research of Diabetes mellitus. Diabetes is a chronic systemic disease characterized by disorders in the metabolism of insulin, carbohydrate, fat, and protein as well as in the structure and function of blood vessels. Currently, diabetes is a leading cause of death in the United States, and more than sixteen million Americans are believed to have this disease. Intensive management of blood sugars through frequent monitoring is effective to prevent, or at least manage, the progression of diabetic complications such as kidney failure, heart disease, gangrene, and blindness.
Maintaining blood glucose levels near normal levels is typically achieved by frequently monitoring the blood glucose. Currently the most common method of sensing is a colorimetric/electro-enzymatic approach, which is invasive. In short, the colorimetric/electro-enzymatic approach requires blood to be drawn and tested. This often requires a finger stick to draw blood each time a reading is needed. In sum, this approach is typically time-consuming and quite painful.
Minimally invasive approaches based on needle-type enzyme sensors (e.g. glucose oxidase) have been investigated as a less painful method of estimating blood glucose concentrations. Such approaches, however, have well-known limitations of measurement of glucose in interstitial fluid. For example, such approaches often suffer from a limitation on the accuracy and stability of the glucose measurement. In this regard, the chemical instability and/or external biocompatibility issues tend to adversely affect the signal sensitivity and stability of the sensor over time. As such, there exists a need for a minimally invasive approach that overcomes one, some or all of the well-known limitations.